Mike Stock, the co-writer of a generation of wholesome hits such as Kylie Minogue's I Should Be So Lucky, has hit out against the "relentless torrent of sex-driven imagery" that young people are exposed to in music videos and on TV.

Stock, part of the Stock, Aitken Waterman hit songwriting team of the 1980s and 1990s, has criticised the fashion for raunchy videos by stars such as Rihanna and Christina Aguilera – whose overtly sexual performances on last year's X Factor attracted thousands of complaints.

"Pop music in this country is almost completely dominated by American acts who have taken sexualised imagery, dance moves and lyrical content way beyond the limits of decency," Stock said in an open letter calling for broadcasters to toughen up their explicit content standards.

Stock added: "As far as music is concerned it has been a slow but unmistakable descent into pornography." He singled out material such as Nicole Scherzinger's "overtly sexual" performance on Britain's Got Talent this year and called on the BBC and ITV to take the lead in cracking down on raunchy content.

Stock's letter comes on the heels of the publication of the Bailey report into the commercialisation and sexualisation of young people by the media. The report called for the introduction of cinema-style classifications and tightening the 9pm watershed, so that performances such as those seen on the X Factor are not repeated.

"I have concerns that the report has let the broadcasters off the hook. All broadcasters need to take responsibility for their own output," he said. "Eventually, even sites like YouTube will need to face up to their obligations."

Stock argued that the watershed is "irrelevant" in the digital age, with services such as the BBC iPlayer allowing children to access any TV content they wish. He added that "you can't sticker a download" with explicit warnings, as happens with CDs and DVDs.

Stock believes the TV industry regulator, Ofcom, is "little more than a passive observer", that can only react after material has aired. "But what's the point after the horse has bolted?"

He also laments the disappearance of pop chart shows such as Top of the Pops, which he believes had higher standards.

"There's no broadcast opportunity for pop," he said. "Bring back pop music for young people, expose it on television and drive all this sexually explicit trash back to the stone age where it belongs. Let's all get behind a weekly chart of the bestselling pop records. The promotion of which is something that the BBC and ITV should take the lead on. Everyone else will soon follow."

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